That s what I think about the last two pages:
The unknown character is carrying two bounties: the one of Rufy and the one of another Pirate. These two are the targets of his plan.
In the freezed room lives a person/monster who is delegate to go after/kill one or both of those two charachters.
The person/monster left the strawhat, so it choosed to go after Luffy.
After all, of that Hat is the real treasure, Dofla would have had some reaction when he saw Rufy wearign one.